Process for killing salmonella in fish meal

ABSTRACT

A process for exposing fish meal to dichloromonofloromethane gas or Freon 21 gas to kill Salmonella.

United States Patent [191 McConville PROCESS FOR KILLING SALMONELLA INFISH MEAL [75] Inventor: Thomas P. McConville, Long Beach,

Calif.

[73] Assignee: Westgate-California Foods, Inc., San Diego, Calif.

[22] Filed: Oct. 19, 1970 [21] Appl. No.: 81,670

[52] US. Cl ..99/158, 99/225 [51] Int. Cl. ..A23l 3/34, A220 25/00 [58]Field of Search ..21/58; 99/189, 7,158, 225,

[56] References Cited UNITED STATES PATENTS 3,579,359 5/1971 schjolberg..99/l95 SOURCE FISH MEAL

I45] Mar. 27, 1973 3,097,099 7/1963 Bechmann ..99/158 3,249,442 5/1966Keyes et a1. ..99/195 3,136,642 6/1964 Bachenger ..99/l97 2,849,3238/1958 Micleleton ..99/l89 3,117,832 1/1964 Thomas ..21/58 PrimaryExaminer-Norman Yudkoff Attorney-Carl R. Brown [57] ABSTRACT A processfor exposing fish meal to dichloromonofloromethane gas or Freon 21 gasto kill Salmonella.

10 Claims, 1 Drawing Figure SOURCE OF COMPRESSED AIR CYCLONE SEPARATORBARREL SOURCE OF FREON 2| VACUUM O AIR LOCK CHAMBER PROCESS FOR KILLINGSALMONELLA IN FISH MEAL BACKGROUND OF THE INVENTION Fish meal, thatgenerally comprises scrapes of fish including bones, skin, the meat offish and other leftovers in the processing of fish, is used for manypurposes including as a food product for animals and the like. In theprocessing, the fish meal normally comprises small particles, that aredried and sterilized in a heated dryer. 1

The fish meal is then moved from the dryer to a storage bin. When thefish meal leaves the dryer, it is supposed to be sterilized and normallythe sterilizing process does kill most bacteria. However the fish mealstill usually becomes contaminated by the time it reaches the storagebin. This can result from various conditions, such as openings in thetransportation system or the storage bin, contamination of thetransportation equipment and other such conditions. The fish mealnormally cools off in the storage bin and then is stored in the bin forseveral hours to several days before it is removed and transported tothe point of use. Thus in the processing of fish meal, the fish meal isoften sterilized of all bacteria but later becomes contaminated in thetransportation to the storage bin and in storage in the storage bin. Sowhen the fish meal is moved to the packaging or truck distributionstage, it is again contaminated.

While there are many bacteria that can cause difficulty in later use offish meal, Salmonella is particularly bothersome because it is difficultto kill even in the sterilizing process, and it is even more difficultto keep from contaminating the fish meal in movement from the dryer andsterilizer to the storage bin and to points of delivery.

Thus it is advantageous to have a process for drying fish meal andstoring the fish meal until time for distribution, and then forsterilizing the fish meal immediately prior to delivery in the mannerthat does not require that the fish meal be cooled thereafter. It isfurther advantageous to have a means for de-contaminating fish meal ofSalmonella.

SUMMARY OF THE INVENTION In the process of this invention, dried fishmeal is exposed to a gas having the chemical namedichloromonofloromethane, the formula CHCL F and the common name Freon21. Hereinafter this gas will be referred to by its common name Freon21. The sufficient exposure of the fish meal to Freon 21 gas will killall Salmonella as well as other bacteria in the fish meal. Inexperimentation it has been established that while the blowing of gasthrough fish meal will kill all Salmonella in Salmonella contaminatedfish meal, it is also possible to kill all salmonella in fish meal byexposing the fish meal to Freon 21 gas in a vacuum chamber for a periodof at least about one-half minute. This latter process permits thedisburse-ment of the Freon 21 gas into the fish meal, which passesthrough the vacuum chamber in a thin layer on a conveyor belt, in aneffi-' cient system operation.

This process makes it possible to efficiently process fish meal from itsorigination through storage and later transportation to point of use inan effici'ent manner that still assures the killing of all Salmonellaand other bacteria at the point of transportation to the point of use.Thus the fish meal can be dryed and sterilized, moved by air to storageand stored in the storage bin for any given period of time. When it isdesired to dispense the fish meal from the storage bin fortransportation to point of use, the fish meal then may be passed througha Freon 21 environment in an air lock chamber, killing all Salmonella inthe fish meal immediately prior to loading the fish meal in a de-con- 0taminated transportation means.

It is therefore an object of this invention to provide a new andimproved process for de-contaminating fish meal.

It is another object of this invention to provide a new and improvedmethod for de-contaminating fish meal and especially to kill allSalmonella in fish meal.

It is another object of this invention to provide a new and improvedprocess for drying, sterilizing, storing and distributing to points ofuse fish meal free of bacteria and Salmonella that contaminate the fishmeal during storage.

It is another object of this invention to provide a new and improvedmethod of processing the sterilization of fish meal by the use of Freongas in a manner that the Freon gas is controlled in such-use.

Other objects and many advantages of this invention will become moreapparent upon the reading of the following detailed description and anexamination of the drawing wherein like reference numerals designatelike parts throughout and in which:

FIG. 1 is a schematic view of an embodiment of the process of thisinvention.

Referring now to the drawing, fish meal provided from any known source 8is inserted into a' dryer 10. While the dryer 10 may have any knownconfiguration, in one exemplary embodiment it is similar to a cementkiln wherein fish meal is inserted into a long tube that is heated. Thetube, which is inclined, rolls continuously causing the fish meal to bemoved progressively down the tube to the exit end. The fish meal isnormally dried in the dryer 10 to the point that it only has about threeor four per cent moisture. For example, the fish meal may be passedthrough the dryer 10 for about 5 minutes at about 450 to 500 F., whereinthe fish meal will be dryed and sterilized. The fish meal is then movedfrom the dryer 10 by a conveyor 12, that may be of the screw type,through an air lock valve 14 into pipe 20. The air lock valve 14 canhave rotating vanes 15 that function in the known manner to move thefish into the air line 20 while restricting the passage of air from line20 back through the air lock 14.

Air is supplied from a suitable source of pressurized air 9 throughinput line 11 and air lock seal valve 18 into pipe 20. Pipe 20, has asufficient diameter than when it receives the dryed and sterilized fishmeal through input line 16, it carries the fish meal by movement of airthrough pipe 20 to a cyclone storage bin 22. For example, the pipe 20may have a diameter of approximately 15 inches and a length ofapproximately 500 feet and the input air supply can be about 2,200 cubicfeet per minute at about atmospheric pressure. The fish meal isseparated from the air in the storage bin 22 that has a conical bottomthat feeds the fish meal through a suitable discharge valve and line 34to the main storage bin 36. The air in turn moves upwardly through vent24 and through a filter bag device 26 that removes the light and finefish meal from the air. The clean air 28 is discharged from the filterbag, with the fine fish meal passing out discharge 30 to a barrel 32.The powderized fine fish meal in barrel 32 is either used for specificpurposes or is thrown away.

The storage bin 36 comprises the main storage area for the fish meal andthe fish meal normally cools in this bin. As is usually the case, thefish meal in passing from the dryer through conveyor 12, air line 20,the cyclone storage bin 22 to the main storage area 36, becomescontaminated with Salmonella and possibly other bacteria. In other casesthe fish meal may have been contaminated with Salmonella upon leavingthe dryer 10. The fish meal is usually stored in the main storage areauntil it can be transported either in bulk or in suitable packages toother points of use. Since the fish meal may be stored in the storagebin for a period of several hours to several days, during this period oftime the bacteria and Salmonella can multiply increasing thecontamination.

In this process, prior to transportation to point of use, the fish mealis passed through a gas lock rotating valve 40 that serially passesquantities of the fish meal into the air lock chamber 42. Air lockchamber 42 is a vacuum chamber, with the vacuum being drawn by asuitable known mechanism 50 through a valve 52. When a suitable vacuumis reached, then Freon 21 gas under a pressure of for example, 12 PSIabsolute, is passed into the chamber 42 to the degree that the vacuum inthe chamber is about 10 inches of mercury. The fish meal is depositedfrom the air lock mechanism 40 onto the conveyor 62 in the direction ofarrows 54 so that it spreads in a thin layer onto conveyor 62 that movesthe fish meal through the air lock chamber 42 in the direction of arrows64. The fish meal passes over the end of conveyor 62 and out an air lockpassage device 66 and through a de-contaminated line 68 to ade-contaminated truck 72 for transportation to the point of use.

The conveyor belt 62 moves on rollers 58 and 60 and is powered by anysuitable power means, not shown. The fish meal, is moved on the belt 62at a degree of speed that the fish meal is in the air lock chamber for aperiod of at least about one-half minute. It has been found that throughexperimentation that an exposure time of 5 seconds is not sufficient tokill all of the Salmonella. Further an exposure time of seconds was notsufficient to kill all of the Salmonella in the fish meal. However anexposure time of one-half minute resulted in the killing of allSalmonella in the fish meal. Subsequent experiments with exposure timesof 1 minute, 5 minutes, 10 minutes, and minutes did not increase theeffect of killing all Salmonella in the fish meal. Thus the optimum timefor exposure is in the order of one-half to 1 minute.

The fish meal, when deposited on the belt 62, is very porous. Thus thegas permeates the fish meal easily and the fish meal is easily spreadvery thinly onto the belt 62. While the belt may have a porous texture,it has a sufficiently fine texture to carry the fish meal thereon.

It has also been found possible to blow Freon 21 into the fish meal asit passes along conveyor 62 in the chamber 42, and thus achieve thekilling of Salmonella. However the use of the air lock vacuum chamberprovides a somewhat more efficient structure that makes the use of theFreon 21 easier to control.

In actual operation of the air lock chamber, the vacuum device 50 drawsa vacuum in chamber 42 periodically and then a charge of Freon 21 gasfrom source 44 is inserted through line 48 into the chamber 42periodically. Thus rather than using a continuous drawing of a vacuumand inserting of Freon 21 gas into chamber 42, this is accomplished bythe periodic drawing of the vacuum and inserting a Freon 21 gas chargeinto the chamber 42, which permits using a smaller amount of Freon 21gas. However it is within this invention to make the insertion andwithdrawal of Freon 21 gas continuous.

Having described my invention, 1 now claim.

1. A process for exposing fish meal to dichloromonofloromethane gas tokill bacteria and especially Salmonella comprising the steps of,

moving the dryed fish meal into an exposure withdichloromonofloromethane gas,

exposing said fish meal to the dichloromonofloromethane gas for aminimum time period of 30 seconds, and

removing said fish meal from exposure with the dichloromonofloromethanegas.

2. A process for exposing fish meal to dichloromonofloromethane gas tokill Salmonella as claimed in claim 1 characterized by said exposurebeing made in a chamber at a slight vacuum.

3. A process as claimed in claim 1 characterized by said exposure beingin a chamber filled with dichloromonofloromethane gas at a vacuum ofabout ten inches of mercury.

4. A process as claimed in claim 3 including a step in said exposingstep of,

moving said fish meal in a thin layer through said chamber.

5. A process as claimed in claim 4 including the steps of,

periodically and substantially evacuating said chamber of thedichloromonofloromethane gas, and

recharging said substantially evacuated chamber withdichloromonofloromethane gas.

6. A process as claimed in claim 4 including the steps of,

drying said fish meal prior to moving said fish meal into the exposurewith dichloromonofloromethane gas.

7. A process as claimed in claim 6 including the step of,

dispersing said fish meal by air prior to moving said fish meal into theexposure with the dichloromonofloromethane gas.

8. A process for exposing fish meal to dichloromonofloromethane gas tokill bacteria and especially Salmonella, comprising the steps of,

placing fish meal into exposure with dichloromonofloromethane gas, andexposing said fish meal to the the drying and sterilizing the fish meal,

storing in storage the fish meal for later use, and

exposing the fish meal to dichloromonofloromethane gas to kill bacteriaand Salmonella immediately prior to delivery from said storage. 5

2. A process for exposing fish meal to dichloromonofloromethane gas to kill Salmonella as claimed in claim 1 characterized by said exposure being made in a chamber at a slight vacuum.
 3. A process as claimed in claim 1 characterized by said exposure being in a chamber filled with dichloromonofloromethane gas at a vacuum of about ten inches of mercury.
 4. A process as claimed in claim 3 including a step in said exposing step of, moving said fish meal in a thin layer through said chamber.
 5. A process as claimed in claim 4 including the steps of, periodically and substantially evacuating said chamber of the dichloromonofloromethane gas, and recharging said substantially evacuated chamber with dichloromonofloromethane gas.
 6. A process as claimed in claim 4 including the steps of, drying said fish meal prior to moving said fish meal into the exposure with dichloromonofloromethane gas.
 7. A process as claimed in claim 6 including the step of, dispersing said fish meal by air prior to moving said fish meal into the exposure with the dichloromonofloromethane gas.
 8. A process for exposing fish meal to dichloromonofloromethane gas to kill bacteria and especially Salmonella, comprising the steps of, placing fish meal into exposure with dichloromonofloromethane gas, and exposing said fish meal to the dichloromonofloromethane gas for a sufficient time to kill Salmonella.
 9. A process for exposing fish meal to dichloromonofloromethane gas as claimed in claim 8 in which, said fish meal is exposed to the dichloromonofloromethane gas continuously.
 10. A process of de-contaminating fish meal prior to delivery comprising the steps of, drying and sterilizing the fish meal, storing in storage the fish meal for later use, and exposing the fish meal to dichloromonofloromethane gas to kill bacteria and Salmonella immediately prior to delivery from said storage. 